1. Field of the Invention
The present invention relates to a technique for displaying high-quality freeze video.
2. Description of the Related Art
A video processing system such as a digital television applies various types of video processing such as interlace/progressive (IP) conversion, noise reduction, color adjustment, and resolution conversion to input video data and then outputs the resulting video data to a panel to display the video. In such a video processing system, a plurality of video processing units sequentially performs video processing while receiving and transmitting video data via a frame memory. Further, the video processing system stores video data corresponding to a plurality of frames for adjustment of the timing to input the video data and the timing to output the video data to the panel and also for the video processing units that refer to the video data of the plurality of frames.
Currently, the full high-definition (HD) resolution (1920×1080) is a common resolution of digital televisions. However, standardization of higher-resolution video such as 4K2K (4096×2160) and ultra-high definition (7680×4320) has been developed, and there have been demands for video processing systems for displaying such video. Further, various types of new video processing have been discussed to further enhance image quality. In other words, the sizes of video data to be handled and the number of types of video processing to be performed on video data have been increasing. Thus, the amount of video data written to and read from a frame memory when sequential video processing is performed via the frame memory has dramatically been increasing.
In response to the foregoing situation, methods have been discussed that use a compression and decompression technique to reduce the amount of data written to and read from a frame memory.
Japanese Patent Application Laid-Open No. 2010-171609 discusses a video processing system in which input video data is compressed and then written to a frame memory and video data read from the frame memory is decompressed and then subjected to video processing.
Japanese Patent Application Laid-Open No. 2010-171609 also describes that the compression rate of video is increased if the video is to be displayed on a still screen or a high-definition television (TV), whereas the compression rate of the video is decreased to reduce the amount of power consumed by the apparatus to drive a battery.
Further, Japanese Patent Application Laid-Open No. 2000-308016 describes that when a freeze command (to select a still image mode) is input while video that is compressed according to the Moving Picture Experts Group (MPEG) standards is displayed, an intra-coded picture (I picture) is displayed among the I picture, a predictive coded picture (P picture), and a bipredictive coded picture (B picture).
In this case, however, a low-quality video frame may be freeze displayed in response to the freeze command.
For example, when the frame memory stores a plurality of video frames having different compression rates, if the freeze command is input to freeze display the video frame having the highest compression rate, low-quality video is freeze displayed.
Furthermore, for example, if the freeze command is input when the compression rates of the video frames stored in the frame memory are temporarily high due to occurrence of a scene change or the like, a low-quality video frame stored in the frame memory may be freeze displayed.